Officials say a white supremacist who went on a shooting rampage inside a Sikh temple before being killed by law enforcement was an Army veteran who likely mistook the Sikhs for Muslims.

Witnesses say 40-year-old Wade Michael Page walked into the Sikh Temple of Wisconsin in suburban Milwaukee on Sunday morning and opened fire, murdering six people and critically wounding three more, including a police officer. Although initial reports said Page was one of several men who took part in the killings, it is now believed that he acted alone.

According to authorities, Page was a military veteran who joined the Army in 1992 as a repairman for the Hawk missile system before becoming a psychological operations specialist. He was discharged in 1998.

Mark Potok, a senior fellow at the Southern Poverty Law Center, said Page was a "frustrated neo-Nazi" who had spent the last decade as part of the white-power music scene, playing in bands with names like Definite Hate and End Apathy whose songs have lyrics that talk about carrying out genocide against Jews and other minorities.

But since Potok added there's no research showing that white supremacists hate Sikhs, Sunday's attack was almost certainly the result of Page mistaking his victims for Muslims or Arabs.

Although there are about a half-million Sikhs in the US, the majority of the 500-year-old religion's 27 million followers live in India. But since 9/11, Sikhs have inadvertently become targets of anti-Muslim bias, with the New York-based Sikh Coalition reporting more than 700 hate crimes and fielding thousands of complaints about workplace discrimination and racial profiling.

"We never thought this could happen to our community," said Devendar Nagra, whose sister escaped injury by hiding as the gunman fired in the temple's kitchen. "We never did anything wrong to anyone."